Problem: $ { {-5} \times \left[\begin{array}{rr}{4} & {1} \\ {-1} & {0} \\ {4} & {4}\end{array}\right] = {?} } $
Explanation: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rr}{-5}\times{4} & {-5}\times{1} \\ {-5}\times{-1} & {-5}\times{0} \\ {-5}\times{4} & {-5}\times{4}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{-20} & {-5} \\ {5} & {0} \\ {-20} & {-20}\end{array}\right]}$